Polycom IPXXX Lifters?

Sorry, this is sort of off topic as far as asterisk is concerned! I’ve got a bazillion Polycom IP501’s out in the field and one of my customers had asked me to get them some headset’s lifters etc… No problem right? Wrong! I can’t seem to find a single lifter that works with the Polycom phones. The handset rests on the phone from the top, not the bottom, so every lifter I’ve tried just flings the handset off the phone…

Does anyone have any experience with lifters/brands that work well with Polycom’s?

Thanks in advance, I’m out of ideas!